Thread: Gecko G540 - special offer

Thanks for the heads up on that

Received an answer back from Gecko re shipping.
Cost for USPS or Fedex is $US43.

[Fedex MAY be slightly cheaper and is the usual method that gecko use.]

To get the special price, you need to put 'OVERSTOCK SPECIAL' in the special instruction section of the checkout page.

Just ordered mine

I got lucky and won one of these on the weekend BBQ. Can't wait to get it into my new machine

Originally Posted by seafurymike

I got lucky and won one of these on the weekend BBQ. Can't wait to get it into my new machine

Makes up for having to put up with the Melbourne weather
Congratulations.

One less G540 at the special price. Arrived while I was in tassie.

One less component to get. Now for the motors!

Hi Geoff,
Nice colletion of goodies there.
I think you have a busy time ahead of you if you are going to fit up all of those drivers.

Hi Rod,
I think I got a little carried away with the G250's
I figured that they were never going to repeat the introductory price so I got the maximum order they'd accept. (Plus it ever hurts to have a spare or two, just in case).

I got the heat sinks in the latest order as I couldn't find anyone locally who would hard anodize for an affordable price. All of the commercially available heatsinks I looked at were standard anodizing and easily scratched. Gecko still haven't provided any recommendations as to acceptable insulating material to use with (potentially) conductive heatsinks.
I'm hoping Ch4is goes ahead with his order for motors from MS-Motor. I'll have all the bits I need then, no excuse not to get building.

Hi Geoff,
As you know this electrickery (thanks John) is not my strong point but I have not seen a heatsink insulated - that means nothing by the way. .

I would have thought by grounding the heatsink through the mounting it would protect your board.

Insulating it might hold the heat to the driver board but if it is the right thing to do then perhaps a piece of PCB would do the trick. I am replying here because you have me worried as I have not insulated mine and with my half cocked comments it is bound to prompt somebody to set me straight.

On the G250/G251, the MOSFETs that drive the motors are at whatever voltage your power supply provides so they must be insulated from ground, and each other. In the case of the G251, the insulation is provided by the small black heat sinks provided (this heat sink is an optional extra for the G250).
The anodising on aluminium acts as an insulator so if you're using an anodised heatsink, it should be OK. The problem is that the anodised layer is very thin (5 to 30microns) and very soft so easily scratched. Hard anodising is useful for this application as the layer is thicker (50 microns) and very hard (70C Rockwell).

Now I've got the little heat sinks from Gecko, I can bolt these to a bigger heat sink from Jaycar or DSE. I'm sure I'm more concerned about this than I need to be. As long as I'm careful in preparing a plain anodised heat sink, I'm sure it would be OK. But just in case ...

Get these from Jaycar, CAT. NO. HP1155 Pack of 20 for $3.80

Cut them to appropriate size and use between the MOSFETS and your heatsink for the G250s (the one that comes without a heatsink)

Worth noting that the G251s are assembled without any heatsink compound at all. Gecko obviously don't think it necessary.

Makes for limited heat transfer. If you hold them up to the light and look carefully you can see air gaps between some of the MOSFETS and the heatsink.

I put some heat transfer compound on my G251s. Just the smallest amount. Don't over do it.

Greg

Ignorance was bliss no now you guys have me worried.

I got the model with the heatsink and put some heat transfer compound in there. I noticed the light between the chip and the heatsink as well so I put a reasonable amount of the compound in there to fill the gap.

What are the risks if I have overdone it and if so should I remove some of it?

Any that squeezes out is just excess and won't contribute to how well it works. It is just messy that's all.

Greg

Thanks